The one-way clutch in the automatic transmission controls rotation of a gear forming a part of the planetary gear mechanism so that the planetary gear mechanism may be automatically varied in speed in response to operation of the centrifugally operated clutch. In general, the one-way clutch comprises a ratchet pawl supporting plate integrally connected to said gear, a ratchet supporting member having annularly disposed ratchet teeth adjacent the ratchet pawl supporting plate and secured to a fixed construction member, and a plurality of ratchet pawls journalled on the ratchet pawl supporting plate for movement to engage and disengage the ratchet teeth. In this regard, the ratchet pawls are brought into engagement with the ratchet teeth when the automatic transmission is in a first operative state, to hold the gear in its locked state, whereas the ratchet pawls are disengaged from the ratchet teeth when the transmission is in a second operative state, to release the gear.
In the prior art construction, the plurality of ratchet pawls are all placed in coincidence with the ratchet teeth in their engaging phase. Therefore, if the ratchet pawls should impinge upon the tips of the ratchet teeth and be repelled therefrom in a repeated manner when the automatic transmission is shifted from the second operative state to the first operative state, power is not transmitted, giving rise to the disadvantage of decreased durability of the ratchet pawls.